The overall objectives continue to be the resolution of the mitochondrial oxidative phosphorylation system and reconsitution of the activity with the resolved purified components. Such reconstitution with a minimum number of components would provide unequivocal evidence for the detailed molecular mechanism of energy transduction in mammalian cells. Work in this laboratory during the previous years has yielded a number of soluble proteins which are capable of restoring oxidative phosphorylation activity to a suitably depleted submitochondrial particle.